1. Field of the Invention
This invention relates generally to devices and methods for generating. particle beams, and more particularly, to electron accelerators for generating electron beams of different energies.
2. Background of the Invention
Standing wave electron beam accelerators have found wide usage in medical accelerators where the high energy electron beam is employed to generate x-rays for therapeutic and diagnostic purposes. Electron beam generated by an electron beam accelerator can also be used directly or indirectly to kill infectious pests, to sterilize objects, to change physical properties of objects, and to perform testing and inspection of objects, such as radioactive containers and concrete structures.
When using an electron beam accelerator for various applications, it is desirable that the accelerator be capable of generating electron beam at various prescribed energy levels. For example, for a certain application, it may be desirable to have an accelerator that can generate electron beams at 8 MeV and 5 MeV. It is also desirable that the generated electron beam at each of the different energy modes has a sharp and well-focused energy spectrum. However, existing accelerators may not be able to accomplish these objectives easily and/or satisfactorily.